3 ms·

EVa have back seats and trunks just like ICE, and they need to be usable by the vehicle owner just the same so I’m not sure I see the relevance. For retrofitti

EVa have back seats and trunks just like ICE, and they need to be usable by the vehicle owner just the same so I’m not sure I see the relevance. For retrofitting, locating some batteries in the engine bay is possible. This seems to be avoided by ev manufacturers in favour of locating a monolithic battery pack under the passenger compartment, for weight distribution, simplicity, and (I assume) safety reasons. Physically swappable battery packs isn’t feasible because of the sheer weight of the packs (a leaf 40k pack for example is 210kg). Plus each car manufacturer has different specs and shape packs. Fortunately we already have a completely fungible, extremely portable unit that can be hot-swapped into every EV at nearly any location just like petrol - a kWh of electricity. Today it takes a bit of time to fast charge, but again with visible-on-the-horizon breakthroughs in battery tech e.g. solid state, fast charge times could drop from ~30 minutes to 3.

titzer 6y ago
Of course if you are designing an EV from scratch you want to put the weight of the battery low and in the center for best stability, but with a conversion you gotta find space wherever. Gas tanks are already pretty low and central for the same reason, but clearly an EV battery pack is a lot denser than a full tank of gasoline. Swappable battery packs clearly wouldn't be a single piece, as there are going to be a variety of different bays and sizes. They'd need to be smaller, portable, and stackable, like rectangles or hexagons. It's not really that hard to do if you design for it. If the batteries are under the car then a lift or underground bay you drive onto is fairly easy to do. Or you could just have a kind of dolly that slides under the car and can detach/reattach them. The fact that we never really thought in this direction seems like a blind spot. I mean, look at how pit crews for racing work. The whole car is designed to be swappable in seconds flat, and also for minimum weight and maximum speed. It's just engineering and design investment.

titzer 6y ago

Of course if you are designing an EV from scratch you want to put the weight of the battery low and in the center for best stability, but with a conversion you gotta find space wherever. Gas tanks are already pretty low and central for the same reason, but clearly an EV battery pack is a lot denser than a full tank of gasoline. Swappable battery packs clearly wouldn't be a single piece, as there are going to be a variety of different bays and sizes. They'd need to be smaller, portable, and stackable, like rectangles or hexagons. It's not really that hard to do if you design for it. If the batteries are under the car then a lift or underground bay you drive onto is fairly easy to do. Or you could just have a kind of dolly that slides under the car and can detach/reattach them. The fact that we never really thought in this direction seems like a blind spot. I mean, look at how pit crews for racing work. The whole car is designed to be swappable in seconds flat, and also for minimum weight and maximum speed. It's just engineering and design investment.